Multi-speed transmission

ABSTRACT

A family of transmission gearing arrangements each establish at least one reverse gear ratio and between nine and fifteen forward gear ratios. A shiftable gearing arrangement establishes a variety of gear ratios speed ratio between the input and a first shaft. In some embodiments, a fixed speed ratio is established upstream or downstream of the shiftable gearing arrangement. In reverse and low gear ratios, a low clutch couples the first shaft to the output. In the high gear ratios, a combining planetary gear set establishes a linear speed relationship between the first shaft, a second shaft rotating at a speed proportional to the input, and the output.

TECHNICAL FIELD

This disclosure relates to the field of automatic transmissions formotor vehicles. More particularly, the disclosure pertains to anarrangement of gears, clutches, and the interconnections among them in apower transmission.

BACKGROUND

Many vehicles are used over a wide range of vehicle speeds, includingboth forward and reverse movement. Some types of engines, however, arecapable of operating efficiently only within a narrow range of speeds.Consequently, transmissions capable of efficiently transmitting power ata variety of speed ratios are frequently employed. When the vehicle isat low speed, the transmission is usually operated at a high speed ratiosuch that it multiplies the engine torque for improved acceleration. Athigh vehicle speed, operating the transmission at a low speed ratiopermits an engine speed associated with quiet, fuel efficient cruising.Typically, a transmission has a housing mounted to the vehiclestructure, an input shaft driven by an engine crankshaft, and an outputshaft driving the vehicle wheels, often via a differential assemblywhich permits the left and right wheel to rotate at slightly differentspeeds as the vehicle turns.

SUMMARY OF THE DISCLOSURE

In one embodiment, a transmission includes an input, an output, firstand second shafts, and first and second gearing arrangements. The firstgearing arrangement selectively establishes a plurality of proportionalspeed relationships between the input and the first shaft. The secondgearing arrangement i) imposes a linear speed relationship among thefirst shaft, the second shaft, and the output, ii) selectively couplesthe first shaft to the output, and iii) imposes a proportional speedrelationship between the input and the second shaft. The linear speedrelationship may be fixedly imposed by a planetary gear set orselectively imposed by a planetary gear set in combination with aclutch. The first shaft may be directly selectively coupled to theoutput by a clutch or the selective coupling may be accomplished by aplanetary gear set with a first element fixedly coupled to the secondshaft, a second element fixedly coupled to the output, and a clutch thatselectively couples the third element to either the first element or thesecond element. The proportional speed relationship between the inputand the second shaft may be either a fixed or selective and may be adirect drive relationship.

In a second embodiment, a transmission includes an input, an output, afirst shaft, and first and second gearing arrangements. The firstgearing arrangement selectively establishes a plurality of proportionalspeed relationships between the input and the first shaft. The secondgearing i) selectively imposes a linear speed relationship among thefirst shaft, the input, and the output, and ii) selectively couple thefirst shaft to the output.

In a third embodiment, a transmission includes an output, first throughseventh shafts, three gearing arrangements, and a collection of brakesand clutches. The first gearing arrangement establishes fixedproportional speed relationships among the first, second, and thirdshafts such that the first shaft rotates slowest of the three and thethird shaft rotates fastest of the three. Either the second shaft or thethird shaft may be fixedly coupled to an input. The second gearingarrangement establishes a fixed linear speed relationship among thefourth, fifth, sixth, and seventh shafts. The third gearing arrangementselectively imposes a linear speed relationship among the sixth shaft,the third shaft, and the output. The third gearing arrangement mayinclude a planetary gear set and a high clutch. A low clutch selectivelycouples the sixth shaft to the output. First and second brakesselectively hold the fourth and fifth shafts, respectively, againstrotation. First and second clutches selectively couple the first shaftto the fourth and seventh shafts, respectively. A third clutchselectively couples the second shaft to the fifth shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic view of a first transmission gearing arrangement.

FIG. 2 is schematic view of a second transmission gearing arrangement.

FIG. 3 is schematic view of a third transmission gearing arrangement.

FIG. 4 is schematic view of a fourth transmission gearing arrangement.

FIG. 5 is schematic view of a fifth transmission gearing arrangement.

FIG. 6 is schematic view of a sixth transmission gearing arrangement.

FIG. 7 is schematic view of a seventh transmission gearing arrangement.

FIG. 8 is schematic view of an eighth transmission gearing arrangement.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments can take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentinvention. As those of ordinary skill in the art will understand,various features illustrated and described with reference to any one ofthe figures can be combined with features illustrated in one or moreother figures to produce embodiments that are not explicitly illustratedor described. The combinations of features illustrated providerepresentative embodiments for typical applications. Variouscombinations and modifications of the features consistent with theteachings of this disclosure, however, could be desired for particularapplications or implementations.

A gearing arrangement is a collection of rotating elements and shiftelements configured to impose specified speed relationships among therotating elements. Some speed relationships, called fixed speedrelationships, are imposed regardless of the state of any shiftelements. Other speed relationships, called selective speedrelationships, are imposed only when particular shift elements are fullyengaged. A linear speed relationship exists among an ordered list ofrotating elements when i) the first and last rotating element in thegroup are constrained to have the most extreme speeds, ii) the speeds ofthe remaining rotating elements are each constrained to be a weightedaverage of the first and last rotating element, and iii) when the speedsof the rotating elements differ, they are constrained to be in thelisted order, either increasing or decreasing. The speed of an elementis positive when the element rotates in one direction and negative whenthe element rotates in the opposite direction. A discrete ratiotransmission has a gearing arrangement that selectively imposes avariety of speed ratios between an input shaft and an output shaft.

A group of rotating elements are fixedly coupled to one another if theyare constrained to rotate as a unit in all operating conditions.Rotating elements can be fixedly coupled by spline connections, welding,press fitting, machining from a common solid, or other means. Slightvariations in rotational displacement between fixedly coupled elementscan occur such as displacement due to lash or shaft compliance. One ormore rotating elements that are all fixedly coupled to one another maybe called a shaft. In contrast, two rotating elements are selectivelycoupled by a shift element when the shift element constrains them torotate as a unit whenever it is fully engaged and they are free torotate at distinct speeds in at least some other operating condition. Ashift element that holds a rotating element against rotation byselectively connecting it to the housing is called a brake. A shiftelement that selectively couples two or more rotating elements to oneanother is called a clutch. Shift elements may be actively controlleddevices such as hydraulically or electrically actuated clutches orbrakes or may be passive devices such as one way clutches or brakes. Tworotating elements are coupled if they are either fixedly coupled orselectively coupled.

An example transmission is schematically illustrated in FIG. 1.Transmission housing 10 is fixedly mounted with respect to the vehicle.Input 12 rotates about an input axis. Input 12 is driven by the vehicleengine, preferably via a launch device such as a torque converter thatpermits the engine to idle while the input 12 is stationary. Output 14rotates about an output axis parallel to and offset from the input axis.Output 14 drives the vehicle wheels, preferably via a differential whichmay be located on another axis.

The transmission of FIG. 1 utilizes three simple planetary gear sets 50,60, and 70. A planet carrier 52 rotates about the output axis andsupports a set of planet gears 58 such that the planet gears rotate withrespect to the planet carrier. External gear teeth on the planet gearsmesh with external gear teeth on a sun gear 54 and with internal gearteeth on a ring gear 56. The sun gear and ring gear are supported torotate about the output axis. Gear sets 60 and 70 are similarlystructured except that the sun gears, carriers, and ring gears aresupported for rotation about the input axis. A simple planetary gear setis a type of gearing arrangement that imposes a fixed linear speedrelationship among the sun gear, the planet carrier, and the ring gear.Other known types of gearing arrangements also impose a fixed linearspeed relationship among three rotating elements. For example, a doublepinion planetary gear set imposes a fixed linear speed relationshipbetween the sun gear, the ring gear, and the planet carrier.

The transmission of FIG. 1 also utilizes two pairs of axis transfergears. Axis transfer gears 80 and 84 are supported to rotate about theinput axis while axis transfer gears 82 and 86 are supported forrotation about the output axis. Axis transfer gear 80 meshes with axistransfer gear 82 while axis transfer gear 84 meshes with axis transfergear 86. Meshing axis transfer gears impose a fixed proportional speedrelationship. The gear with a greater number of gear teeth will rotateslower than, and in the opposite direction from, the gear with fewergear teeth. Illustrative ratios of gear teeth for each axis transfergear set and each planetary gear set are listed in Table 1.

TABLE 1 Gear 82/Gear 80 1.034 Gear 86/Gear 84 1.593 Ring 56/Sun 54 1.750Ring 66/Sun 64 1.816 Ring 76/Sun 74 2.649

In the transmission of FIG. 1, axis transfer gear 86 is fixedly coupledto sun gear 54 by first shaft 16. Axis transfer gear 82 is fixedlycoupled to carrier 52 by second shaft 18. Output 14 is fixedly coupledto ring gear 56. Axis transfer gear 84, carrier 62, and ring gear 76 arefixedly coupled by third shaft 20. Ring gear 66 is fixedly coupled tocarrier 72. Shaft 16 is selectively coupled to output 14 by low clutch30. Input 12 is selectively coupled to axis transfer gear 80 by highclutch 40 and selectively coupled to sun gear 64 by first clutch 90. Sungear 74 is selectively coupled to input 12 by second clutch 92 andselectively held against rotation by first brake 94. Finally, thecombination of ring gear 66 and carrier 72 is selectively held againstrotation by second brake 96 and selectively coupled to input 12 by thirdclutch 98. The terms low clutch and high clutch are labels only and donot imply a physical location.

As shown in Table 2, engaging the shift elements in combinations ofthree establishes eleven forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. An X indicates thatthe shift element transmits torque in that speed ratio. An (X) indicatesthe clutch can be applied but is not required to establish the speedratio. In 5th gear, clutches 30 and 40 establish the power flow pathbetween input 12 and output 14. Any one of the remaining shift elementsmay also be applied. Applying clutch 98 in 5th gear ensures that allsingle and two step shifts from 5th gear can be accomplished by engagingonly one shift element and releasing only one shift element. When thegear sets have tooth number ratios as indicated in Table 1, the speedratios have the values indicated in Table 2. Note that the speed ratiois positive in reverse and negative in the forward ratios. An additionalaxis transfer gear pair between output 14 and the differential causesthe wheels to rotate in the same direction as the input in forward andin the opposite direction in reverse.

TABLE 2 30 40 90 92 94 96 98 Ratio Step Rev X X X 4.22 94% 1^(st) X X X−4.49 2^(nd) X X X −2.39 1.88 3^(rd) X X X −1.59 1.50 4^(th) X X X −1.151.38 5^(th) X X (X) −1.03 1.12 6^(th) X X X −0.97 1.06 7^(th) X X X−0.86 1.13 8^(th) X X X −0.78 1.10 9^(th) X X X −0.72 1.09 10^(th) X X X−0.66 1.09 11^(th) X X X −0.60 1.09

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of planetary gear sets 60 and 70and shift elements 90, 92, 94, 96, and 98 selectively impose a pluralityof proportional speed relationships between input 12 and third shaft 20.Specifically, engaging the shift elements in various combinations of twoimposes one reverse speed relationship, two underdrive speedrelationships, a direct drive speed relationship, and one overdrivespeed relationship. The combination of these components and axistransfer gears 84 and 86 selectively impose a plurality of speedrelationships between input 12 and first shaft 16. Combining planetarygear set 50 imposes a fixed linear speed relationship among first shaft16, second shaft 18, and output 14. The combination of high clutch 40and axis transfer gears 80 and 82 selectively establish a proportionalspeed relationship between input 12 and second shaft 18. In other words,when clutch 40 is engaged, shaft 18 is constrained to rotate at a speedproportional to input 12.

Another example transmission is schematically illustrated in FIG. 2. Thetransmission of FIG. 2 utilizes four simple planetary gear sets 50, 100,110, and 120 and two pairs of axis transfer gears, 88 and 82 and 84 and86. Illustrative ratios of gear teeth for each axis transfer gear setand each planetary gear set are listed in Table 3.

TABLE 3 Gear 82/Gear 88 1.000 Gear 86/Gear 84 1.471 Ring 56/Sun 54 2.500Ring 106/Sun 114 2.243 Ring 116/Sun 114 2.171 Ring 126/Sun 124 2.943

In the transmission of FIG. 2, axis transfer gear 86 is fixedly coupledto sun gear 54 by first shaft 16. Output 14 is fixedly coupled to ringgear 56. Axis transfer gear 88 and sun gear 114 are fixedly coupled toinput 12. Axis transfer gear 84, carrier 102, and ring gear 126 arefixedly coupled by third shaft 20. Ring gear 106 is fixedly coupled tocarrier 112. Ring gear 116 is fixedly coupled to carrier 122. Carrier 52is selectively directly coupled to shaft 16 by low clutch 32 andselectively coupled to shaft 18 by high clutch 42. Sun gear 104 isselectively held against rotation by first brake 140. Sun gear 124 isselectively coupled to input 12 by first clutch 142 and selectively heldagainst rotation by second brake 144. Finally, the combination of ringgear 116 and carrier 122 is selectively held against rotation by thirdbrake 146 and selectively coupled to input 12 by second clutch 148.

As shown in Table 4, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 3, the speed ratios havethe values indicated in Table 4. Note that the speed ratio is positivein reverse and negative in the forward ratios. An additional axistransfer gear pair between output 14 and the differential causes thewheels to rotate in the same direction as the input in forward and inthe opposite direction in reverse.

TABLE 4 32 42 140 142 144 146 148 Ratio Step Rev X X X 4.33 64% 1^(st) XX X −6.74 2^(nd) X X X −4.36 1.55 3^(rd) X X X −2.81 1.55 4^(th) X X X−2.13 1.32 5^(th) X X X −1.47 1.45 6^(th) X X X −1.10 1.34 7^(th) X X X−1.00 1.10 8^(th) X X X −0.97 1.04 9^(th) X X X −0.89 1.09 10^(th) X X X−0.83 1.07 11^(th) X X X −0.80 1.04 12^(th) X X X −0.76 1.04 13^(th) X XX −0.75 1.03 14^(th) X X X −0.71 1.04 15^(th) X X X −0.67 1.07

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of planetary gear sets 100, 110,and 120 and shift elements 140, 142, 144, 146, and 148 selectivelyimpose a plurality of proportional speed relationships between input 12and third shaft 20. Specifically, engaging the shift elements in variouscombinations of two imposes one reverse speed relationship, fourunderdrive speed relationships, a direct drive speed relationship, andone overdrive speed relationship. The combination of these componentsand axis transfer gears 84 and 86 selectively impose a plurality ofspeed relationships between input 12 and first shaft 16. Axis transfergears 80 and 82 establish a fixed proportional speed relationshipbetween input 12 and second shaft 18. Combining planetary gear set 50,low clutch 32, and high clutch 42 collectively impose two selectivespeed relationships. First, when low clutch 32 is engaged, first shaft16 is operatively coupled to output 14 because all of the elements ofsimple planetary gear set 50 rotate as a unit. Second, when high clutch42 is engaged, a linear speed relationship is imposed among first shaft16, second shaft 18, and output 14.

Another example transmission is schematically illustrated in FIG. 3. Inthe transmission of FIG. 3, input 12 and output 14 rotate about a commonaxis. The transmission of FIG. 3 utilizes three simple planetary gearsets 50, 150, and 160 and a Ravigneaux gear set 170. Planet carrier 172supports two set of planet gears. External gear teeth on long planetgears 178 mesh with external gear teeth on sun gear 174 and withinternal gear teeth on ring gear 176. External gear teeth on shortplanet gears 179 mesh with external gear teeth on sun gear 175 and withthe external gear teeth on the long planet gears 178. Carrier 172, sungears 174 and 175, and ring gear 176 are each supported to rotate abouta common axis. Ravigneaux gear set 170 imposes a fixed linear speedrelationship among sun gear 174, planet carrier 172, ring gear 176, andsun 175. Other known types of gearing arrangements also impose a fixedlinear speed relationship among four rotating elements. For example, twoplanetary gear sets, each either simple or double pinion type, whereintwo elements of one gear set are fixedly coupled to two elements of theother gear set, collectively impose a fixed linear speed relationshipbetween four shafts. Illustrative ratios of gear teeth for each gear setof FIG. 3 are listed in Table 5.

TABLE 5 Ring 56/Sun 54 1.842 Ring 156/Sun 154 1.634 Ring 166/Sun 1641.919 Ring 176/Sun 174 2.237 Ring 176/Sun 175 2.742

In the transmission of FIG. 3, sun gears 154 and 164 are fixedly heldagainst rotation. Input 12 is fixedly coupled to ring gear 156. Carrier152 is fixedly coupled to ring gear 166 by fourth shaft 22. Ring gear176 is fixedly coupled to sun gear 54 by first shaft 16. Output 14 isfixedly coupled to ring gear 56 and selectively directly coupled toshaft 16 by low clutch 30. Carrier 52 is selectively coupled to input 12by high clutch 44. Sun gear 174 is selectively held against rotation byfirst brake 180. Carrier 162 is selectively coupled to sun gear 174 byfirst clutch 184 and selectively coupled to sun gear 175 by secondclutch 186. Finally, carrier 172 is selectively held against rotation bysecond brake 182 and selectively coupled to fourth shaft 22 by thirdclutch 188.

As shown in Table 6, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 5, the speed ratios havethe values indicated in Table 6.

TABLE 6 30 44 180 182 184 186 188 Ratio Step Rev X X X −5.49 82% 1^(st)X X X 6.72 2^(nd) X X X 3.77 1.78 3^(rd) X X X 2.45 1.54 4^(th) X X X1.84 1.33 5^(th) X X X 1.40 1.32 6^(th) X X X 1.11 1.26 7^(th) X X X1.00 1.11 8^(th) X X X 0.95 1.06 9^(th) X X X 0.87 1.09 10^(th) X X X0.80 1.08 11^(th) X X X 0.76 1.06 12^(th) X X X 0.72 1.06 13^(th) X X X0.68 1.05 14^(th) X X X 0.65 1.06 15^(th) X X X 0.61 1.06

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 160 and 170 and shiftelements 180, 182, 184, 186, and 188 selectively impose a plurality ofproportional speed relationships between fourth shaft 22 and first shaft16. Specifically, engaging the shift elements in various combinations oftwo imposes one reverse speed relationship, four underdrive speedrelationships, and two overdrive speed relationships. Gear set 150establishes a fixed underdrive speed relationship between input 12 andfourth shaft 22. In combination, these components impose a plurality ofspeed relationships between input 12 and first shaft 16. Combiningplanetary gear set 50 and high clutch 44 collectively selectivelyestablish a linear speed relationship among first shaft 16, input 12,and output 14.

Another example transmission is schematically illustrated in FIG. 4. Thetransmission of FIG. 4, like the transmission of FIG. 3, utilizes threesimple planetary gear sets 50, 150, and 160 and a Ravigneaux gear set170. Illustrative ratios of gear teeth for each gear set are listed inTable 5.

In the transmission of FIG. 4, sun gears 154 and 164 are fixedly heldagainst rotation. Input 12 is fixedly coupled to ring gear 156 andfixedly coupled to carrier 52. Carrier 152 is fixedly coupled to ringgear 166 by fourth shaft 22. Ring gear 176 is fixedly coupled to sungear 54 by first shaft 16. Output 14 is selectively directly coupled toshaft 16 by low clutch 30 and selectively coupled to ring gear 56 byhigh clutch 46. Sun gear 174 is selectively held against rotation byfirst brake 180. Carrier 162 is selectively coupled to sun gear 174 byfirst clutch 184 and selectively coupled to sun gear 175 by secondclutch 186. Finally, carrier 172 is selectively held against rotation bysecond brake 182 and selectively coupled to fourth shaft 22 by thirdclutch 188.

As shown in Table 7, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 5, the speed ratios havethe values indicated in Table 7.

TABLE 7 30 46 180 182 184 186 188 Ratio Step Rev X X X −5.49 82% 1^(st)X X X 6.72 2^(nd) X X X 3.77 1.78 3^(rd) X X X 2.45 1.54 4^(th) X X X1.84 1.33 5^(th) X X X 1.40 1.32 6^(th) X X X 1.11 1.26 7^(th) X X X1.00 1.11 8^(th) X X X 0.95 1.06 9^(th) X X X 0.87 1.09 10^(th) X X X0.80 1.08 11^(th) X X X 0.76 1.06 12^(th) X X X 0.72 1.06 13^(th) X X X0.68 1.05 14^(th) X X X 0.65 1.06 15^(th) X X X 0.61 1.06

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 160 and 170 and shiftelements 180, 182, 184, 186, and 188 selectively impose a plurality ofproportional speed relationships between fourth shaft 22 and first shaft16. Specifically, engaging the shift elements in various combinations oftwo imposes one reverse speed relationship, four underdrive speedrelationships, and two overdrive speed relationships. Gear set 150establishes a fixed underdrive speed relationship between input 12 andfourth shaft 22. In combination, these components impose a plurality ofspeed relationships between input 12 and first shaft 16. Gear sets 150and 160 collectively establish fixed proportional speed relationshipsamong i) carrier 162, ii) the combination of carrier 152 and ring gear166, and iii) ring gear 156 such that ring gear 156 rotates faster thanthe other two and carrier 162 rotates slower than the other two.Combining planetary gear set 50 and high clutch 46 collectivelyselectively establish a linear speed relationship among first shaft 16,input 12, and output 14.

Another example transmission is schematically illustrated in FIG. 5. Thetransmission of FIG. 5 utilizes three simple planetary gear sets 50,160, and 190 and a Ravigneaux gear set 170. Illustrative ratios of gearteeth for each gear set of FIG. 5 are listed in Table 8.

TABLE 8 Ring 56/Sun 54 1.842 Ring 166/Sun 164 1.919 Ring 176/Sun 1742.237 Ring 176/Sun 175 2.742 Ring 196/Sun 194 1.634

In the transmission of FIG. 5, sun gears 164 and 194 are fixedly heldagainst rotation. Input 12 is fixedly coupled to ring gear 166. Ringgear 176 is fixedly coupled to ring gear 196 by third shaft 20. Carrier192 is fixedly coupled to sun gear 54 by first shaft 16. Output 14 isfixedly coupled to ring gear 56 and selectively directly coupled toshaft 16 by low clutch 30. Carrier 52 is selectively coupled to input 12by high clutch 44. Sun gear 174 is selectively held against rotation byfirst brake 180. Carrier 162 is selectively coupled to sun gear 174 byfirst clutch 184 and selectively coupled to sun gear 175 by secondclutch 186. Finally, carrier 172 is selectively held against rotation bysecond brake 182 and selectively coupled to input 12 by third clutch188.

As shown in Table 6, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 8, the speed ratios havethe values indicated in Table 6.

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 160 and 170 and shiftelements 180, 182, 184, 186, and 188 selectively impose a plurality ofproportional speed relationships between input 12 and third shaft 20.Specifically, engaging the shift elements in various combinations of twoimposes one reverse speed relationship, four underdrive speedrelationships, and two overdrive speed relationships. Gear set 190establishes a fixed underdrive speed relationship between third shaft 20and first shaft 16. In combination, these components impose a pluralityof speed relationships between input 12 and first shaft 16. Combiningplanetary gear set 50 and high clutch 44 collectively selectivelyestablish a linear speed relationship among first shaft 16, input 12,and output 14.

Another example transmission is schematically illustrated in FIG. 6. Thetransmission of FIG. 6 utilizes three simple planetary gear sets 50,160, and 200 and a Ravigneaux gear set 170. Illustrative ratios of gearteeth for each gear set of FIG. 6 are listed in Table 9.

TABLE 9 Ring 56/Sun 54 1.842 Ring 166/Sun 164 1.919 Ring 176/Sun 1742.237 Ring 176/Sun 175 2.742 Ring 206/Sun 204 1.634

In the transmission of FIG. 6, sun gears 164 and 204 are fixedly heldagainst rotation. Input 12 is fixedly coupled to carrier 202 and to ringgear 166. Second shaft 18 is fixedly coupled to ring gear 206. Ring gear176 is fixedly coupled to sun gear 54 by first shaft 16. Output 14 isfixedly coupled to ring gear 56 and selectively directly coupled toshaft 16 by low clutch 30. Carrier 52 is selectively coupled to secondshaft 18 by high clutch 42. Sun gear 174 is selectively held againstrotation by first brake 180. Carrier 162 is selectively coupled to sungear 174 by first clutch 184 and selectively coupled to sun gear 175 bysecond clutch 186. Finally, carrier 172 is selectively held againstrotation by second brake 182 and selectively coupled to input 12 bythird clutch 188.

As shown in Table 10, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 9, the speed ratios havethe values indicated in Table 10.

TABLE 10 30 42 180 182 184 186 188 Ratio Step Rev X X X −3.40 82% 1^(st)X X X 4.17 2^(nd) X X X 2.34 1.78 3^(rd) X X X 1.52 1.54 4^(th) X X X1.14 1.33 5^(th) X X X 0.87 1.32 6^(th) X X X 0.69 1.26 7^(th) X X X0.62 1.11 8^(th) X X X 0.59 1.06 9^(th) X X X 0.54 1.09 10^(th) X X X0.50 1.08 11^(th) X X X 0.47 1.06 12^(th) X X X 0.44 1.06 13^(th) X X X0.42 1.05 14^(th) X X X 0.40 1.06 15^(th) X X X 0.38 1.06

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 160 and 170 and shiftelements 180, 182, 184, 186, and 188 selectively impose a plurality ofproportional speed relationships between input 12 and first shaft 16.Specifically, engaging the shift elements in various combinations of twoimposes one reverse speed relationship, four underdrive speedrelationships, and two overdrive speed relationships. Gear set 200establishes a fixed overdrive speed relationship between input 12 andsecond shaft 18. Gear sets 200 and 160 collectively establish fixedproportional speed relationships among i) carrier 162, ii) thecombination of input 12, carrier 202, and ring gear 166, and iii) ringgear 206 such that ring gear 206 rotates faster than the other two andcarrier 162 rotates slower than the other two. Combining planetary gearset 50 and high clutch 42 collectively selectively establish a linearspeed relationship among first shaft 16, second shaft 18, and output 14.

Another example transmission is schematically illustrated in FIG. 7. Thetransmission of FIG. 7 utilizes three simple planetary gear sets 50,160, and 200 and a Ravigneaux gear set 170. Illustrative ratios of gearteeth for each gear set of FIG. 7 are listed in Table 9.

In the transmission of FIG. 7, sun gear 164 is fixedly held againstrotation. Input 12 is fixedly coupled to carrier 202 and to ring gear166. Ring gear 206 is fixedly coupled to carrier 52 by second shaft 18.Ring gear 176 is fixedly coupled to sun gear 54 by first shaft 16.Output 14 is fixedly coupled to ring gear 56 and selectively coupled tocarrier 52 by low clutch 34. Sun gear 204 is selectively held againstrotation by high brake 41. Sun gear 174 is selectively held againstrotation by first brake 180. Carrier 162 is selectively coupled to sungear 174 by first clutch 184 and selectively coupled to sun gear 175 bysecond clutch 186. Finally, carrier 172 is selectively held againstrotation by second brake 182 and selectively coupled to input 12 bythird clutch 188.

As shown in Table 11, engaging the shift elements in combinations ofthree establishes fifteen forward speed ratios and one reverse speedratio between input shaft 12 and output shaft 14. When the gear setshave tooth number ratios as indicated in Table 9, the speed ratios havethe values indicated in Table 11.

TABLE 11 34 41 180 182 184 186 188 Ratio Step Rev X X X −3.40 82% 1^(st)X X X 4.17 2^(nd) X X X 2.34 1.78 3^(rd) X X X 1.52 1.54 4^(th) X X X1.14 1.33 5^(th) X X X 0.87 1.32 6^(th) X X X 0.69 1.26 7^(th) X X X0.62 1.11 8^(th) X X X 0.59 1.06 9^(th) X X X 0.54 1.09 10^(th) X X X0.50 1.08 11^(th) X X X 0.47 1.06 12^(th) X X X 0.44 1.06 13^(th) X X X0.42 1.05 14^(th) X X X 0.40 1.06 15^(th) X X X 0.38 1.06

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 160 and 170 and shiftelements 180, 182, 184, 186, and 188 selectively impose a plurality ofproportional speed relationships between input 12 and first shaft 16.Specifically, engaging the shift elements in various combinations of twoimposes one reverse speed relationship, four underdrive speedrelationships, and two overdrive speed relationships. Gear set 200 andhigh brake 41 selectively establish an overdrive speed relationshipbetween input 12 and second shaft 18. Combining planetary gear set 50and low clutch 34 collectively selectively couple output 14 to firstshaft 16.

Another example transmission is schematically illustrated in FIG. 8. Thetransmission of FIG. 8 utilizes four simple planetary gear sets 50, 150,210, and 220. Illustrative ratios of gear teeth for each gear set ofFIG. 8 are listed in Table 12.

TABLE 12 Ring 56/Sun 54 1.500 Ring 156/Sun 154 3.000 Ring 216/Sun 2152.400 Ring 226/Sun 224 2.200

In the transmission of FIG. 8, sun gear 154 is fixedly held againstrotation. Input 12 is fixedly coupled to ring gear 156 and to carrier52. Carrier 212 is fixedly coupled to ring gear 226 by first shaft 16.Fourth shaft 22 is fixedly coupled to carrier 152. Output 14 is fixedlycoupled to ring gear 56 and selectively directly coupled to shaft 16 bylow clutch 30. Sun gear 54 is selectively coupled to first shaft 16 byhigh clutch 48. Sun gear 214 and sun gear 224 are selectively heldagainst rotation by first brake 230 and selectively coupled to fourthshaft 22 by first clutch 234. Carrier 222 is selectively held againstrotation by second brake 232. Finally, fourth shaft 22 is selectivelycoupled to ring gear 216 by second clutch 236.

As shown in Table 13, engaging the shift elements in combinations ofthree establishes nine forward speed ratios and one reverse speed ratiobetween input shaft 12 and output shaft 14. When the gear sets havetooth number ratios as indicated in Table 12, the speed ratios have thevalues indicated in Table 13.

TABLE 13 30 48 230 232 234 236 Ratio Step Rev X X X −2.93 94% 1^(st) X XX 3.11 2^(nd) X X X 1.89 1.65 3^(rd) X X X 1.33 1.42 4^(th) X X X 1.001.33 5^(th) X X X 0.86 1.17 6^(th) X X X 0.76 1.13 7^(th) X X X 0.691.11 8^(th) X X X 0.60 1.15 9^(th) X X X 0.53 1.14

Various combinations of gear sets and shift elements impose particularspeed relationships. The combination of gear sets 210 and 220 and shiftelements 230, 232, 234, and 236 selectively impose a plurality ofproportional speed relationships between fourth shaft 22 and first shaft16. Specifically, engaging the shift elements in various combinations oftwo imposes one reverse speed relationship, two underdrive speedrelationships, and a direct drive speed relationship. Gear set 150establishes a fixed underdrive speed relationship between input 12 andfourth shaft 22. In combination, these components impose a plurality ofspeed relationships between input 12 and first shaft 16. Combiningplanetary gear set 50 and high clutch 48 collectively selectivelyestablish a linear speed relationship among first shaft 16, input 12,and output 14.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes caninclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, embodimentsdescribed as less desirable than other embodiments or prior artimplementations with respect to one or more characteristics are notoutside the scope of the disclosure and can be desirable for particularapplications.

What is claimed is:
 1. A transmission comprising: an input; an output; afirst gearing arrangement configured to impose a plurality of selectiveproportional speed relationships between the input and a first shaft;and a second gearing arrangement configured to i) impose a linear speedrelationship among the first shaft, a second shaft, and the output, ii)selectively couple the first shaft to the output, and iii) impose aproportional speed relationship between the input and the second shaft.2. The transmission of claim 1 wherein the first gearing arrangementcomprises: a third gearing arrangement configured to impose a pluralityof selective proportional speed relationships between the input and athird shaft, including at least one selective proportional speedrelationship wherein the third shaft rotates faster than the input; anda fourth gearing arrangement configured to fixedly impose a proportionalspeed relationship between the third shaft and the first shaft whereinthe first shaft rotates slower than the third shaft.
 3. The transmissionof claim 2 wherein the third gearing arrangement comprises: a firstsimple planetary gear set having a first sun gear, a first carrierfixedly coupled to the third shaft, and a first ring gear; a secondsimple planetary gear set having a second sun gear, a second carrierfixedly coupled to the first ring gear, and a second ring gear fixedlycoupled to the first carrier; a first clutch configured to selectivelycouple the input to the first sun gear; a second clutch configured toselectively couple the input to the second sun gear; a first brakeconfigured to selectively hold the second sun gear against rotation; asecond brake configured to selectively hold the first ring gear and thesecond carrier against rotation; and a third clutch configured toselectively couple the input to the first ring gear and the secondcarrier.
 4. The transmission of claim 2 wherein the third gearingarrangement comprises: a first simple planetary gear set having a firstsun gear, a first carrier fixedly coupled to the third shaft, and afirst ring gear; a second simple planetary gear set having a second sungear fixedly coupled to the input, a second carrier fixedly coupled tothe first ring gear, and a second ring gear; a third simple planetarygear set having a third sun gear, a third carrier fixedly coupled to thesecond ring gear, and a third ring gear fixedly coupled to the firstcarrier; a first brake configured to selectively hold the first sun gearagainst rotation; a first clutch configured to selectively couple theinput to the third sun gear; a second brake configured to selectivelyhold the third sun gear against rotation; a third brake configured toselectively hold the second ring gear and the third carrier againstrotation; and a second clutch configured to selectively couple the inputto the second ring gear and the third carrier.
 5. The transmission ofclaim 2 wherein the third gearing arrangement comprises: a second simpleplanetary gear set having a second sun gear fixedly held againstrotation, a second carrier, and a second ring gear fixedly coupled tothe input; a Ravigneaux gear set having a third sun gear, a fourth sungear, a third carrier, and a third ring gear fixedly coupled to thethird shaft; a first brake configured to selectively hold the third sungear against rotation; a second brake configured to selectively hold thethird carrier against rotation; a first clutch configured to selectivelycouple the second carrier to the third sun gear; a second clutchconfigured to selectively couple the second carrier to the fourth sungear; and a third clutch configured to selectively couple the input tothe third carrier.
 6. The transmission of claim 2 wherein the fourthgearing arrangement comprises: a third axis transfer gear fixedlycoupled to the third shaft; and a fourth axis transfer gear fixedlycoupled to the first shaft and in continuous meshing engagement with thethird axis transfer gear.
 7. The transmission of claim 2 wherein thefourth gearing arrangement comprises: a first simple planetary gear sethaving a first sun gear fixedly held against rotation, a first carrierfixedly coupled to the first shaft, and a first ring gear fixedlycoupled to the third shaft.
 8. The transmission of claim 1 wherein thefirst gearing arrangement comprises: a fifth gearing arrangementconfigured to impose a plurality of selective proportional speedrelationships between a fourth shaft and the first shaft; and a sixthgearing arrangement configured to fixedly impose a proportional speedrelationship between the input and the fourth shaft wherein the fourthshaft rotates slower than the input.
 9. The transmission of claim 8wherein the fifth gearing arrangement comprises: a second simpleplanetary gear set having a second sun gear fixedly held againstrotation, a second carrier, and a second ring gear fixedly coupled tothe fourth shaft; a Ravigneaux gear set having a third sun gear, afourth sun gear, a third carrier, and a third ring gear fixedly coupledto the first shaft; a first brake configured to selectively hold thethird sun gear against rotation; a second brake configured toselectively hold the third carrier against rotation; a first clutchconfigured to selectively couple the second carrier to the third sungear; a second clutch configured to selectively couple the secondcarrier to the fourth sun gear; and a third clutch configured toselectively couple the fourth shaft to the third carrier.
 10. Thetransmission of claim 8 wherein the fifth gearing arrangement comprises:a second simple planetary gear set having a second sun gear, a secondcarrier, and a second ring gear; a third simple planetary gear sethaving a third sun gear fixedly coupled to the second sun gear, a thirdcarrier, and a third ring gear fixedly coupled to the second carrier; afirst brake configured to selectively hold the second sun gear and thethird sun gear against rotation; a second brake configured toselectively hold the third carrier against rotation; a first clutchconfigured to selectively couple the fourth shaft to the second sun gearand the third sun gear; and a second clutch configured to selectivelycouple the fourth shaft to the second ring gear.
 11. The transmission ofclaim 8 wherein the sixth gearing arrangement comprises: a first simpleplanetary gear set having a first sun gear fixedly held againstrotation, a first carrier fixedly coupled to the fourth shaft, and afirst ring gear fixedly coupled to the input.
 12. The transmission ofclaim 1 wherein the second gearing arrangement is configured to fixedlyimpose a linear speed relationship among the first shaft, the secondshaft, and the output and to selectively impose a proportional speedrelationship between the input and the second shaft.
 13. Thetransmission of claim 12 wherein the second gearing arrangementcomprises: a first axis transfer gear; a second axis transfer gearfixedly coupled to the second shaft and in continuous meshing engagementwith the first axis transfer gear; a combining simple planetary gear sethaving a combining sun gear fixedly coupled to the first shaft, acombining carrier fixedly coupled to the second shaft, and a combiningring gear fixedly coupled to the output; a low clutch configured toselectively couple the first shaft to the output; and a high clutchconfigured to selectively couple the input to the first axis transfergear.
 14. The transmission of claim 13 wherein the low clutch isconfigured to directly selectively couple the first shaft to the output.15. The transmission of claim 12 wherein the second gearing arrangementcomprises: a first simple planetary gear set having a first sun gear, afirst carrier fixedly coupled to the input, and a first ring gearfixedly coupled to the second shaft; a combining simple planetary gearset having a combining sun gear fixedly coupled to the first shaft, acombining carrier fixedly coupled to the second shaft, and a combiningring gear fixedly coupled to the output; a low clutch configured toselectively couple the first shaft to the output; and a high brakeconfigured to selectively hold the first sun gear against rotation. 16.The transmission of claim 15 wherein the low clutch is configured toselectively couple the first shaft to the output by directly selectivelycoupling the combining carrier to another element of the combiningsimple planetary gear set.
 17. The transmission of claim 1 wherein thesecond gearing arrangement is configured to selectively impose a linearspeed relationship among the first shaft, the second shaft, and theoutput and to fixedly impose a proportional speed relationship betweenthe input and the second shaft.
 18. The transmission of claim 17 whereinthe second shaft is fixedly coupled to the input.
 19. The transmissionof claim 17 wherein the second shaft is constrained to rotate fasterthan the input.
 20. The transmission of claim 17 wherein the secondgearing arrangement comprises: a combining simple planetary gear sethaving a combining sun gear fixedly coupled to the first shaft, acombining carrier, and a combining ring gear fixedly coupled to theoutput; a low clutch configured to selectively couple the first shaft tothe output; and a high clutch configured to selectively couple thesecond shaft to the combining carrier.
 21. The transmission of claim 20wherein the low clutch is configured to directly selectively couple thefirst shaft to the output.
 22. The transmission of claim 20 wherein thelow clutch is configured to selectively couple the first shaft to theoutput by directly selectively coupling the combining carrier to anotherelement of the combining simple planetary gear set.
 23. The transmissionof claim 17 wherein the second gearing arrangement comprises: acombining simple planetary gear set having a combining sun gear, acombining carrier fixedly coupled to the second shaft, and a combiningring gear fixedly coupled to the output; a low clutch configured toselectively couple the first shaft to the output; and a high clutchconfigured to selectively couple the first shaft to the combining sungear.
 24. The transmission of claim 17 wherein the second gearingarrangement comprises: a combining simple planetary gear set having acombining sun gear fixedly coupled to the first shaft, a combiningcarrier fixedly coupled to the second shaft, and a combining ring gear;a low clutch configured to selectively couple the first shaft to theoutput; and a high clutch configured to selectively couple the output tothe combining ring gear.
 25. A transmission comprising: an input; anoutput; a first shaft; a first gearing arrangement configured to imposea plurality of selective proportional speed relationships between thefirst shaft and the input; and a second gearing arrangement configuredto i) selectively impose a linear speed relationship among the firstshaft, the input, and the output, and ii) selectively couple the firstshaft to the output.
 26. A transmission comprising: an output; first,second, third, fourth, fifth, sixth, and seventh shafts; a first gearingarrangement configured to impose fixed proportional speed relationshipsbetween the first, second, and third shafts such that the third shaftrotates faster than the second shaft and the second shaft rotates fasterthan the first shaft; a second gearing arrangement configured to imposea fixed linear speed relationship among the fourth, fifth, sixth, andseventh shafts; a third gearing arrangement configured to selectivelyimpose a linear speed relationship among the sixth shaft, the thirdshaft, and the output; a first brake configured to selectively hold thefourth shaft against rotation; a second brake configured to selectivelyhold the fifth shaft against rotation; a first clutch configured toselectively couple the first shaft to the fourth shaft; a second clutchconfigured to selectively couple the first shaft to the seventh shaft; athird clutch configured to selectively couple the second shaft to thefifth shaft; and a low clutch configured to selectively couple the sixthshaft to the output.
 27. The transmission of claim 26 wherein the thirdshaft is fixedly coupled to an input.
 28. The transmission of claim 26wherein the second shaft is fixedly coupled to an input.